Sowing seeds of life into the galaxy

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Article from New Scientist, by Stephen Battersby.

If there is no life on other planets, let's send it there

EARTH'S first interstellar expedition seems to be a disaster. During the long journey most of the passengers die from radiation sickness. When at last the spacecraft arrives, it crash-lands on the surface of a bleak and barren world. The capsule splits open and the alien air finishes off many of the remaining explorers. Over the ensuing days, some of the few survivors succumb to the extreme temperatures, while others die after drinking from pools of acid.

But one stalwart survives. Soon there is even better news: our explorer divides into two clones. Earth life reproduces for the first time under the light of an alien star. Its offspring mutate and begin to adapt to their new home, eventually spreading across the planet and evolving into new forms of life. That's one small step for a bug, one giant leap for bugkind.

Why would we want to replace Captain Kirk with a bacterium? Because the dream of humans travelling to other stars, while not impossible, may yet turn out to be unfeasible.

If we can't go in person, then instead we could recruit our single-celled cousins as astronauts. "We are at a point now where we almost have the ability to send micro-organisms to other worlds," says Michael Mautner of Virginia Commonwealth University in Richmond. "We can generate a vast amount of life in the universe. It would give our own existence purpose."

The idea that simple life forms could be carried from planet to planet, known as panspermia, is an old one. Ever since the 19th century, scientists have been debating whether life could survive the long journeys between star systems. Mautner thinks the process should not be left to chance.

"I started to become interested in the 1970s, at the height of the cold war and the nuclear arms race, when there were questions about whether we were going to survive," he says. "What if Earth has the only life? Earth will be destroyed eventually, then all life is gone. For me that's a very empty and meaningless universe." The answer, he concluded, is that we should become the agents of panspermia.

He is not alone in advocating directed panspermia, as this idea is known. "Expanding the richness of life in the universe is what we ought to be doing," says Chris McKay, an astrobiologist at the NASA Ames Research Center in Moffett Field, California.

Mautner outlined his ideas for spreading Earth life across the galaxy in a recent paper (Journal of Cosmology, vol 5, p 982). He envisages sending out colony ships filled with microbes and pulled by solar sails. The first solar-sailing craftMovie Camera was launched by Japan's space agency last year, and by Mautner's calculations such craft could reach speeds of up to 150 kilometres a second by swooping close to the sun before unfurling their sails.

Where should we send the first microvoyagers? The obvious target is a young, temperate rocky planet similar to Earth, the kind of planet we may soon start to find thanks to NASA's Kepler mission, launched in 2009. A seeding mission could aim to put a spacecraft in orbit within the habitable zone around the host star, from where it could disperse millions of seed capsules, some of which should end up on the target planet.

But this would not be easy. Such a distant stellar target would need precise targeting, and more critically, the craft would have to slow down to enter orbit around the target star. It could decelerate by using its solar sail to catch the light of the star, but it is not clear whether this would be possible without an active guidance system, which would have to remain in working order for tens of thousands of years. "I would like to stay away from any far-future technologies if possible," says Mautner.

In that case, a softer target might be a disc of gas and dust around a young star, such as Beta Pictoris, 63 light years away. Here the tactics of the swarm come in: "If you send billions of small vehicles, hopefully some will arrive," says Mautner. Each vessel could hold 100,000 freeze-dried bacteria in a capsule just 40 micrometres across, towed behind a sail less than 4 millimetres across. When these seed pods arrive, drag from the gas in the disc would slow them down. As comets and rocky bodies form in the disc, says Mautner, some seed pods will become incorporated and eventually a few should end up on the surfaces of planets.

The journey will take a long, long time. Even at a speed of 150 kilometres per second, the trip to Beta Pictoris would take more than 120,000 years. Can any living organism survive such an epic voyage in space? "That is the biggest open question," says Mautner.

The toughest passengers may be freeze-dried bacteria, which are often stored for long periods in laboratories. Some bacteria can dry themselves out and produce a hardy dormant form called an endospore. There are controversial claims of endospores being revived after being locked in amber for 40 million years, or after being trapped in salt crystals in a cave in New Mexico for 250 million years. Even if some bacteria really can snooze for a quarter of a billion years, though, they are far less likely to survive in space than in a cave.
Dead on arrival

The big danger is cosmic rays - energetic protons and other charged particles that can smash up DNA. We are shielded from most cosmic rays by Earth's atmosphere and the solar wind, but in interstellar space the microbe passengers of a small seed capsule would face the radiation unprotected.

We know that they could cope for a few years, at least. Bacteria have survived for more than 18 months outside the International Space Station. Much longer-term exposure would be more challenging, but might not be terminal, says Lewis Dartnell of University College London, who studies the potential for microbes to survive on Mars. "The numbers might work out if you can send enough microbial voyagers in each capsule. The vast majority would die on the way from radiation, but a tiny fraction would survive." After a million years with negligible shielding, he calculates, about one in a million freeze-dried bacteria would remain alive. At the solar-sail speeds envisaged by Mautner, a million years is long enough to travel 500 light years.

Then again, maybe it does not matter if the bugs are dead on arrival. Last year, Paul Wesson of the Herzberg Institute of Astrophysics in Canada suggested that even the shattered corpses of microbes, just fragments of DNA and other biomolecules, could help life to emerge. He called the idea "necropanspermia".

Alternatively, shielding a few metres thick on the spacecraft would cut out the bulk of cosmic ray damage. Another solution might be to revive the passengers from time to time so they can repair any DNA damage, before suspending their animation again. These options would require much larger spacecraft, though, which would spoil one of Mautner's aims - to make directed panspermia relatively cheap. After all, a project that may not bear fruit for billions of years, and whose success or failure may never be known, seems unlikely to attract vast funds.

The cost of Mautner's lower-tech approach depends on a lot of factors. How many capsules must land on a young planet, say, to achieve a fair chance of some bug becoming established? Mautner guesses a hundred, although McKay feels that is optimistic. "The chances of any particular organism growing or any particular capsule falling on fertile ground is vanishingly small," says McKay. "The good thing is that it's easy to make billions of them."

Billions, perhaps many billions, will be needed. Even the closest planetary systems are tiny targets, and most capsules will miss altogether. They are also moving targets, and we will need ultraprecise measurements of their motions before an unguided mission could succeed. That should be possible with space-based telescope arrays within a few decades, Mautner says.

Marc Millis of the Tau Zero Foundation, which promotes research into interstellar travel, is sceptical. "It's hard to hit interstellar targets, and it is much harder to hit targets with passive sails than with a vehicle that can correct its course as it goes along."

Aim becomes less of a problem in one of Mautner's grander plans. He hopes to seed entire star-forming regions holding dozens of new stars, such as the Rho Ophiuchi cloud, about 500 light years away. That is a big target, no problem to hit. On the downside, such large-scale carpet-bombing would probably need millions of times as many seed capsules as a single planet or planet-forming accretion disc. And once there, most of the intrepid bugs might have wait millions of years, all the while exposed to the hard rain of cosmic radiation, before anything solid forms.

If fleets of simple spacecraft can't do the job, a more high-tech approach will be needed. Sails propelled not by sunlight but by huge lasers in Earth orbit could theoretically reach speeds of thousands of kilometres per second, slashing travel time and radiation exposure, and they could probably be aimed more precisely than sun-catching sails. Advanced robotics could even guide microbial passengers to the most promising havens on new worlds.

While the challenges are huge, there is no doubt that it will be easier to send bacteria than people. They are only very distant cousins of ours, but as far as Mautner is concerned, kin is kin. "Life is one big family, and the purpose of life is to propagate," he says. "If we manage to seed life on a few hundred planets, we can start many chains of evolution. Hopefully some will evolve into intelligent beings."

McKay agrees. "When we look around the universe we see a lot of different things, but the thing that is most interesting, the only thing that is a source of value, is life," he says. "I like the argument that humans should seek to expand the richness and diversity of life."
Complete annihilation

There is a risk that we would be doing the opposite, however. The presence of Earth colonists might prevent new forms of life evolving from scratch. Worse still, the colonists might kill off native life forms.

Consider the opposite situation. "How would we react if another civilisation sent to Earth a directed panspermia package containing alien microbes, and it affected the Earth's biosphere in a negative way?" asks astrobiologist and writer Barry DiGregorio, affiliated with Cardiff University in the UK. If we cannot be sure that microbes won't harm existing life, then we shouldn't send them, he says. "The only reason I can think of to try it, as a last resort, is if the Earth was facing complete annihilation by an impending solar event, asteroid or comet catastrophe."

Others are less worried. "My feeling is that any natives, adapted to their environment, would be better equipped and so outcompete the new arrivals," says Dartnell, "but that might not always be the case."

Proposed space telescopes such as NASA's Terrestrial Planet Finder could check for signs of life on other worlds before capsules are sent. They would not be able to detect the early stages of life, Dartnell says, but they should reveal where a biosphere is well established. If these searches do not find any such signs, it will be evidence that life does not readily get started and needs our helping hand.

If, on the other hand, life is found to be plentiful, there would be no need for directed panspermia. A galaxy teeming with aliens might be a sign that life evolves readily, or spreads rapidly between star systems by natural panspermia, or both. Or maybe, as Carl Sagan suggested in 1966, another civilisation had this idea billions of years ago and successfully spread their seed throughout the galaxy. Was our ancestor the lone survivor of a tiny starship that crash-landed on a bleak and barren planet far from home?

Read more: For a different point of view, see Barry E. DiGregorio's Comment article "Don't send bugs to Mars"

........

The right stuff

If we want to seed distant planets with life, what should we send? The first challenge is to survive the journey, which makes Deinococcus radiodurans - aka Conan the Bacterium - a tempting choice. It is not only extraordinarily radiation-resistant, but can also survive extreme cold and dehydration. However, D. radiodurans cannot form long-lasting endospores and it needs oxygen and organic compounds, which won't be available on a barren new world.

What might be available is methane, hydrogen or sulphide compounds, food to microbes like the ones found around deep-sea vents. "As long as they find an ocean, they could probably find a living," says Lewis Dartnell of University College London. Other obvious candidates include photosynthetic organisms such as cyanobacteria, which could make their own food and produce oxygen into the bargain, although it might take billions of years for oxygen to reach the levels that animals need.

Fertile ground should not be hard to find. Michael Mautner of Virginia Commonwealth University in Richmond has grown algae and even small asparagus plants in pulverised chunks of meteorites (Icarus, vol 158, p 72). "The material is as productive as agricultural soil here on Earth," he says.

Mautner is not planning to sow the galaxy with asparagus, but he does speculate about sending more advanced organisms. It may have taken almost 2 billion years for complex cells to evolve from bacteria, and sending single-celled algae, for example, might bypass an evolutionary bottleneck and speed up the appearance of multicellular organisms. Complex cells would be far less likely to survive an epic trip, though.

To maximise the chances of a few microbes surviving, Mautner suggests sending a diverse mix of simple cells, including extremophiles that thrive in high or low temperatures, fierce acidity and so on. Better still, genetic engineers could create superbugs able to survive extended space travel, exploit many different energy sources and live in a wide range of environments.
 
Good read, thanks for that.

er...haven't really formulated an opinion on that yet so...

...Maybe we could send The Stig to populate other worlds!
 
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^ Well, some say that he can survive the vacuum of space...all we know is, he's called the Stig!
 
The Stig can act as humanity's ambassador if he comes across any alien civilization.

Though I can see the aliens making their own "facts" about the man with no vocal cords.
 
From the beautiful campus of the University of Washington, my alma mater, comes this video lecture by Professor of Bioengineering, Gerald Pollack, entitled Water, Energy and Life: Fresh Views from the Water's Edge.

It presents a new information which tends to unify all science, including physics, biology and even astronomy with regard to water and charge separation. I believe and hope that Famine and TM will find this of great interest.

Although this could be posted under many different threads (Aliens, Creation vs Evolution, etc., or even have a new bespoke thread, I choose to post it here because it sheds new light on Foolkiller's insight on cometary seeding of life in the universe (variation on panspermia), which seems to have inspired the OP.

http://www.youtube.com/watch?v=V7jKL2-B0QA

Respectfully submitted,
Dotini
 
That would be cool... except I have this strange battlestar galactica feel... the life on another planet evolves waaay faster and eventually supasses us, comes back and ****s us up. lol
 
At last humanity is approaching the limits of the solar system with the 1977 space probe Voyager 1. Here, the solar system is defined as the plasma cell enclosed by the heliosheath. Within another 4 years, the craft will be in true interstellar space where a different regime of conditions prevail.


http://www.nasa.gov/mission_pages/voyager/voyager20101213.html
PASADENA, Calif. – The 33-year odyssey of NASA's Voyager 1 spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind.

Now hurtling toward interstellar space some 17.4 billion kilometers (10.8 billion miles) from the sun, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.

The event is a major milestone in Voyager 1's passage through the heliosheath, the turbulent outer shell of the sun's sphere of influence, and the spacecraft's upcoming departure from our solar system.

"The solar wind has turned the corner," said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. "Voyager 1 is getting close to interstellar space."

Our sun gives off a stream of charged particles that form a bubble known as the heliosphere around our solar system. The solar wind travels at supersonic speed until it crosses a shockwave called the termination shock. At this point, the solar wind dramatically slows down and heats up in the heliosheath.

Launched on Sept. 5, 1977, Voyager 1 crossed the termination shock in December 2004 into the heliosheath. Scientists have used data from Voyager 1's Low-Energy Charged Particle Instrument to deduce the solar wind's velocity. When the speed of the charged particles hitting the outward face of Voyager 1 matched the spacecraft's speed, researchers knew that the net outward speed of the solar wind was zero. This occurred in June, when Voyager 1 was about 17 billion kilometers (10.6 billion miles) from the sun.

Because the velocities can fluctuate, scientists watched four more monthly readings before they were convinced the solar wind's outward speed actually had slowed to zero. Analysis of the data shows the velocity of the solar wind has steadily slowed at a rate of about 20 kilometers per second each year (45,000 mph each year) since August 2007, when the solar wind was speeding outward at about 60 kilometers per second (130,000 mph). The outward speed has remained at zero since June.

The results were presented today at the American Geophysical Union meeting in San Francisco.

"When I realized that we were getting solid zeroes, I was amazed," said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again."

Scientists believe Voyager 1 has not crossed the heliosheath into interstellar space. Crossing into interstellar space would mean a sudden drop in the density of hot particles and an increase in the density of cold particles. Scientists are putting the data into their models of the heliosphere's structure and should be able to better estimate when Voyager 1 will reach interstellar space. Researchers currently estimate Voyager 1 will cross that frontier in about four years.

"In science, there is nothing like a reality check to shake things up, and Voyager 1 provided that with hard facts," said Tom Krimigis, principal investigator on the Low-Energy Charged Particle Instrument, who is based at the Applied Physics Laboratory and the Academy of Athens, Greece. "Once again, we face the predicament of redoing our models."
 
Some day Voyager 1 will reach something in the Oort cloud, spin a U turn around it and head straight back towards Earth, impacting on the NASA headquarters as some flaming dust.

Or, after a 200,000 years it returns perfectly in Earth orbit and after a mission to retrieve it inside a cargo capsule and returned to ground the dolphin/human hybrids scientists are amazed to see a new message encoded on the plaque, translated to read
"Return to sender, No junk mail".
 
I believe should the situation arise, we should be tentative to leave our own life forms of life on other planets. For a start, we may not even know if native live forms are living on the planet already, bringing our own life forms could potentially damage and kill existing life forms.

I think for our own survival as a species long term, it's fundamental that we branch out and inhabit other planets, in which case, bringing other forms of life to help our sustainability on other planets is likely to be fundamental.

The question of whether we in inhabit other planets/moons is not a question if, but rather a question of when. Sadly I doubt it will occur in my lifetime.
 
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